18" SIDEWINDER I/O

[jeffbare]

My family has a 1972 18" Sidewinder with a inline 6, 165hp mercruiser. Currently we are running a 21p stock aluminum prop (I know this is the first place to start). The boat tops out about 50mph. I would like to know if anyone has any experience trying to get good performance out of a Sidewinder. I know there is always the option of adding more horse power, but I thought it would be fun to try some other options. The inline 6 is a great motor, doesn't use any gas, and has great skiing torque. Just thought it might be a good project boat. This boat has been in the family since it was special ordered by my dad when he was selling his marina that sold Sidewinders and GlasPlys'. It is the boat I grew up with, and would love to restore it and make it a boat that isn't totally embarassed by my Vegas XT. I would love to get 60 mph out of it if possible.
Thanks,
Jeff

[chris_lacey]

I ran Sidewinders years ago, and I don't think you're going to see 60 with the 250cid inline 6. The 18' with the Mercuiser 260 was refered to as the "60plus". It had 100 more hp than you have. There used to be cams and 4 bbl manifolds available for the inline six since it was the prefered engine in the "Hobby" class of stock car racing and D class dragsters, but I doubt you'll find much, if any left.
I'd enjoy it stock, and go fast in the Vegas.

[delawarerick]

I think the 4.3 v-6 would be a great improvement on speed and is allaround as good on gas if not better. We replaced a 165 with a 205hp v-6 it woke the boat up not a winder. With the rounded pad its hard to exceed 55mph above that and chine walking begins. I run a 16 sidewinder with a v-4 110 with the good heads I have seen 62 on gps but there was soil in my britches cause it was wild driving to say the least. If you run in chop the boat seems to handle better. I think the sidewinder is a timeless stylish boat and worth repowering the design is of the era. Pictures of your boat and the rebuild are always appreciated. We bought this v-6 up in New Jersey I think it was a school motor complete was 3700 ready to bolt up.(one yr warranty) The worst part was making a mount I would think you will have the same problem. We went with 6 inch 3/8 angle alunium which costs 200$ for 4 ft. Rick

[jeffbare]

I think Rick is right, to restore her to her original condition and be happy with that. The problem with going to a V6 or V8 is that I don't think there is room in the engine compartment. With the jump seats on either sides of the cowling, there is barely room for the inline-6. I am not an expert with fiberglass, and would never know where to get the sparkely green flakes to build a new cover.Thanks.
Anybody have suggestions for a prop?
Jeff

[delawarerick]

A through hub 19-20 raker or sst would be good. Larger than 13 now bigger than 137/8. Problem is watch your rpms if not mistaken 4400-4600 rpm is max for that motor. Rick

[jeffbare]

The I-6 has a lot of torque, do you think it would turn a 21P or 23P? Is that too much? Do over the hub props work on the older I/O's? I have a 26" Mazco RE4, the diameter might be too much for that lower unit. I would love to make th eboat a little faster, there really aren't many boats that look as good as the sidewinder in the water when they are running wot.
Jeff

[chris_lacey]

I wouldn't try an overhub. They rev like crazy until they shed the exhaust bubble on take off and it will likely be too much for the old girl. Maybe try a 4 blade like a trophy or rev 4. Good hole shot and pretty efficient. I would try a 20P or so and you will likely still be faster than the aluminum 21.